Exercise devices that simulate climbing stairs (“stair climbers”) have become very popular. Not only are they relatively easy to learn how to use, but also they can, when used properly, provide an excellent cardiovascular workout. Stair climbers, however, have drawbacks in that users can easily “cheat” by leaning or supporting their body weight on an upright portion of the device and by taking short steps. Frequently the users who cheat the most are de-conditioned athletes for whom the device can be the most beneficial. In addition to providing sub-optimal benefits, improper body positioning during exercise can lead to overuse injuries. Another disadvantage of stair climbers is the exercise under normal conditions is fairly demanding. In other words the lowest level of energy expenditure is fairly high. This demands that the user be in fairly good physical condition in order to be able to perform this type of exercise.
One type of exercise device, which seeks to obtain the benefits of stair climbers using a different motion path, is the “cross trainer.” A popular type of cross trainer is the “elliptical” trainer. Examples of the elliptical trainer are set forth in U.S. Pat. Nos. 5,685,804; 5,788,610; and 5,242,343. Many of the more popular devices provide footpads supported on an elongate member that is secured at one end to a flywheel and slidable at the other end. Although these devices can provide a relatively smooth motion, the motion path caused by their configuration can be undesirable for several reasons. Specifically, as the footpad moves back and forth, it is also forced to move through a somewhat significant angular change as well. This forces the ankle to move through dorsa flexion and plantar flexion during the transilitory motion. This motion which appears to be similar to the same motion the foot might move through during normal walking gait, is in fact very different and applies significantly different loading to the body. Many consider this pattern of motion and change in loading to feel unnatural and somewhat stressful at higher loads. It is for this reason that many users of cross trainers use them only at very low load settings. Treadmills, it would appear, offer the best range of intensity of exercise with a fairly natural motion. The problem is that in order to get higher rates of energy expenditure on a treadmill, the user must run. Although running is an excellent form of exercise, it has also been well documented that the impact of running applies significant increases in stress to the body.